Automobiles having an auto-leveling system or an AFS (Adaptive Front-lighting System) are being proposed. The auto-leveling system controls an irradiating direction of headlamps in vertical directions to prevent dazzling oncoming drivers as the result of a change in orientation of the automobile. The AFS controls the irradiating direction to swivel in the right and left directions (e.g. during cornering), to illuminate the direction of travel of the automobile to improve visibility for drivers. Such automobiles are configured to control auto-leveling actuators or swivel actuators, which are provided in a respective lamp, with an ECU (Electronic Control Unit). More specifically, the ECU sends irradiating direction signals to each of the actuators, and each of the actuators controls the irradiating direction of the corresponding lamp based on the irradiating direction signals. However, to improve control of the respective actuators, various control signals need to be transmitted between the ECU and the respective actuators, which increases the number of harnesses coupling therebetween. In such a case, the configuration of the system and maintenance thereof becomes complicated.
To address this problem, SACTs (Smart ACTuators) are being proposed. The SACTs are configured by integrating a microcomputer and various sensors into the actuator to enable separate control from the ECU. According to such a configuration, the SACTs can take over some of the controls from the ECU, so that the number of harnesses between the actuators and the ECU can be reduced. For example, in some situations, an actuator is controlled by the ECU and also has its own microcomputer (a sub-CPU). Feedback control is executed between the actuator and the ECU with respect to the irradiating direction of the lamp, whereby the signals transmitted between the actuator and the ECU as well as the number of harnesses are reduced (see, e.g., Japanese Patent Document JP 2003-260980 A).
For the purpose of downsizing and weight reduction, SACTs use a stepping motor or a DC brushless motor as a driving source for changing the irradiating direction of the lamp. Further, for the purpose of downsizing and cost reduction, the SACTs are not provided with an encoder or a potentiometer which can detect absolute rotational positions of the motor and the irradiating direction. Therefore, although the amount of change in the irradiating direction can be detected as a rotational amount of the motor, the absolute rotational position of the irradiating direction is not detected. Accordingly, to control the absolute position of the irradiating direction, it is necessary to set a reference angular position in advance through a mechanical operation, and to execute directional controls in accordance with an amount of change from the reference angular position. Thus, when the power is turned on so that the SACT is initialized, a reference setting operation for setting the reference angular position is required. In such systems, when the power is turned on so that the ECU is initialized, the ECU sends a reset signal to the SACT to cause the SACT to execute the reference setting operation.
Some systems are configured to provide an independent power supply path for each of the ECU and the SACT, or to provide the ECU and the SACT with CPUs having different specifications, such as set timings. In the systems having such a configuration, in some cases, the ECU and the SACT are separately initialized. For example, only the ECU may be initialized or only the SACT may be initialized. However, as described above, the ECU is configured to send, when it is initialized, the reset signal to cause the SACT to execute the reference setting operation. Therefore, when only the ECU is initialized during a state in which the SACT has not been initialized after the previous reference setting operation, the SACT receives the reset signal from the ECU and again executes the reference setting operation for setting the reference angular position, in spite of the situation that the SACT is already capable of proper operation based on a direction control signal. That is, in a certain situation, the reference setting operation is unnecessarily performed, resulting in a waste of a time until the irradiating direction control is initiated.
On the other hand, when only the SACT is initialized, the reference setting operation for setting the reference angular position is not executed in the SACT because the reset signal is not sent from the ECU. In such a situation, therefore, the SACT cannot properly control the irradiating direction based on the direction control signal from the ECU and, as a result, the irradiating direction of the lamp is directed toward the wrong direction. In this case, it is possible to restore the SACT to a normal condition if the ECU is initialized. However, depending on system configuration, the system may indicate an alert and execute unnecessary fail-safe control upon detection of system malfunction, which unnecessarily causes the driver to feel anxious.